It is known to form blown fibers of polyolefin such as polyethylene or polypropylene. Such meltblown fibers are known for use in wipes and other disposable items.
It is also been known as disclosed in U.S. Pat. No. 4,100,324 Anderson et al. to form nonwoven fabric materials of long thermoplastic polymer microfibers that have entangled therein wood pulp fibers. Such materials have found use in wipes and as absorbent materials for feminine care and incontinent products.
It has been suggested in the British Patent Application Publication No. 2,113,731 of Aug. 10, 1983, that the meltblown fiber having wood pulp fibers may be further supplied during forming with another absorbent material such as a superabsorbent or clay material. It is disclosed in the above United Kingdom Patent Application Publication that powdered superabsorbent may be added to the meltblown material during formation and that the majority of the particles will be entrapped into the material as it is gathered on a forming surface. The addition of superabsorbent particles to meltblown materials have also been suggested in U.S. Pat. No. 4,429,001--Koplin et al.
The use of superabsorbents in combination with fibrous material in an absorbent garment has been suggested by U.S. Pat. No. 4,338,371 Dawn et al. in which a layer of superabsorbent material containing superabsorbent is provided in a garment for utilization by astronauts for extravehicular activity. U.S. Pat. No. 4,297,410 Tsuchiya et al. also discloses a structure wherein a superabsorbent layer is placed between nonwoven fabric layers.
There have been several difficulties in prior materials utilizing superabsorbents. One difficulty has been that the superabsorbent materials exhibit a phenomenon usually referred to as gel-blocking. When this occurs the superabsorbents that are first exposed to liquids swell and block access of the liquid to the remaining superabsorbent. A preferred present practice attempts to overcome the gel-blocking phenomenon by sandwiching either particulate or film forms of superabsorbent between tissue or similar materials. This technique, however, tends to restrict the uptake of fluids by the superabsorbents, and adds cost to the superabsorbent material. Another difficulty with many superabsorbent containing materials is that the hydrogel superabsorbents when wet have an uncomfortable, clammy, slimy feel to them. The use of these materials in applications in which they are exposed to the body has been particularly difficult due to the slimy, unpleasant feel. There also has been difficulty in the processes in which air-forming is used in combination with particulate superabsorbents. Air-forming processes require the removal of air from beneath the forming surface. During air removal the particulate superabsorbents tend to also be removed as they are primarily held by physical entanglement and are not chemically bound with the meltblown thermoplastic fibers. The difficulties caused by sliminess have been attempted to be overcome by effectively burying the superabsorbent containing ply(s) beneath one or more plies that do not contain superabsorbent material.
Therefore, there is a need for an improved combination of superabsorbent material and fibrous material in which gel-blocking is minimal and superabsorbent is not wasted (by passing through the forming process, and being caught by the dust collector), and costly plying to mask the clammy, slimy feel of superabsorbent materials is unnecessary. There is also a need for a nonwoven fibrous material that acts as a matrix in which the particulate superabsorbents may be easily accessible to fluids and may be free to expand.